Condenser



June 16, 1931. J. H. SMITH 1,810,375.

CONDENSER Filed May 29, 1930 2 Sheets-3heet 1 INVENTOR .J. H. EMH'H.

ATTORNEY J1me 1931. J. H.SMITH J 1,810,375

commusrm Filed May 29, 1930 2 Sheets-Sheet 2 FIG 6;

WITNESSES INVENTOR J. H. SMH'H.

M 0%. M F: Q. ATTORNEY Patented June 16, 1931 I I UNITED JOHN. H. summonLANSDOWNE, rnnnsvnvmrn, nssrenon. 'r o wnsrmerrocsn Emcrmc aumcrac'runmc comm,

"P rENr orFlCE i A communities or :rn'mvsnvnnu I 'connmtsna Applicationmed any as, 1980. semi no. 457,325.

end of the tube to the discharge-end. In

My invention relates to apparatus for condenslng gaseous media anparticularly to steam condensers of the multiple pass type and has foran object to provide ap aratus of the character designated which s allbe so constructed and arranged as to effectively utilize the entirecooling surface of the apparatus inorder that it may operate ate very hih heat transfer rate.

It has for a furtfierobject to provide a condenser of the multiple asstype which shall be so constructed an arranged as to provide forimproving longitudinal distri- 'bution of steam to the respective passesof a condenser having a multiple pass tube nest.

These and other objects are efiected by m invention, as will be a parentfrom the 0 lowing description an claims taken in con nection with theaccompanying drawings, forming-a part of'thls application, 111

which:

Fig-11s a view, msectional elevation, ofone form of condenser arranged1n accordance with my invention;

, on the line IL-II of sectional view, taken ig. 1;

Fig. 3-is a view,- in-sectional elevation, of another embodiment of myinvention wherein a considerable portion of the first pass of Fig. 2 isa transve the tube nest is utilized. primarily for coolline VI'VI ofFig. 4; and

ing air and other non-condensable vapors;

ig. 4 1s a view, in sectional elevation, of

myinvention as applied to a condenser ofthe radial flow type; a

Fig. 5 vis a transverse, sectional view through the condenser shell andis taken on the line VV of Fig. 4;

Fig. 6 is a transverse sectional view through the water box and is takenon the particularly to apparatus'of the-surface type intendedrprimarilyfor condensing steam and still more other words, the entrant end f thetube may be termed the cold end while-the discharge end may be termedthe: relatively warm end. As a result of these difierences intemperature, difierent heat heads prevail.

within the condenser shell structure; the region near the entrant .endof. the tube nest having a relatively high heat head and the region nearthe discharge end ofthe tube nest a relatively low heat head.

In condensers of the multiple pass type, such as for example, two passcondensers,

the cooling water ordinarily circulates lonprevails at one end of thecondenser withregard to the first pass tubes and at the opposite end ofthe condenser, with regard .to' the second pass tubes. The regions of'lowheat head created by the respective passes of the tube nest alsoprevail at op--= posite longitudinal ends of the condenser.

As eretofore constructed, the. condenser shell first of all admits thesteam to be condensed to the second pass tube nest; and

there is a natural'tendency revailing in the inlet portion of the shellor the steam to flow in the direction of the region of high heat head.In other words, more steam flows-to the cold end of the second pass andless steam to the warm end. Thisaflords,

an ideal condition inasmuch as the steamis distributed longitudinallyover the tube nest inproportion to its condensing capacity. However, incondensers as. heretofore constructed, this desired condition does notob tain with the'first pass. This is-caused by the fact that very littledistance intervenes between the tubesof thefirst and second pass and,although the heat heads of the of the first pass first pass are thereverse order of the second pass, nevertheless, the steam enters thefirst pass with the same manii'e'r'of distribution as the second pass.In other words, more steam is distributed to the warm end of the firstpass and less steam to the cold end, a condition which is fundamentallywrong.

I have, therefore, conceived the idea of so arranging the condenser thatthe tubes of the first pass are separated from the tubes of the secondpass, transversely, a suflicientdistance so that the steam leaving thesecond pass may before entering the first pass, redistribute itself inaccordance with the changed locations of the heat heads in the firstpass. In this way, proper longitudinal distribution, heretoforeapplicable only to the second pass, is made applicable to the first ass.As a result, the entire tube surface more effectivel utilized.

Referring now to igs. 1 and 2. I show a condenser having a shell 10provided with an inlet 11 for steam to be condensed. Provided at eachend of the shell structure are end tube sheets 12 and 13 and, extendinglongitudinally between the end tube sheets 12 and 13, is a tube nest,generally represented at 14. In the present embodiment, the condenser isof the downflow type in that the lower ortion of the tube nestsubstantially fills t e shell structure and the steam admitted throughthe inlet 11 enters the tube nest mostly through the upper surface ofthe latter. ,4

The tube nest 14 is divided into a firstpass 15 and a second pass 16,the two passes being separated by a longitudinally-extendin distributionspace 17 hereinafter referre to in more detail. Associated with the endtube sheet 12 is a water box 18 provided with a lower inlet connection19 and an upper outlet connection 21. The water box 18 is arranged fortwo pass circulation of cooling water through the tubenest, and, hence,is provided with a central division wall 22 having a flange 23 abuttingthe tube sheet 12 and forming a substantially fluid-tight jointtherewith. Associated with the tube sheet 13 at the other end of thetube nest is a return water box 24 arranged to receive the cooling waterdischarged from the first pass 15 and to direct it to the entrant end ofthe second pass 16.

For supporting the tube nest intermediate of the end tube sheets 12 and13, suitable, longitudinally-spaced intermediate tube support sheets 25are provided which, as shown particularly in Fig. 2, are divided intotransversely spaced upper and second pass sections 26 and lower andfirst pass sections 7. The lower sections 27 are further subdivided intoupper and lower sections 28 and 29 which extend transversely of and aresupported by the condenser shell. The sections 28 and 29 are staggeredlongitudinally,

so as to afford longitudinal circulation of gaseous media through thefirst pass of the tube nest.

Extending longitudinally between the intermediate tube sheet sections 28as well as the adjacent end tube sheets 12 and 13 is an -invertedV-shaped hood 30 which prevents condensate from raining down into acentrally-disposed, triangular-shaped portion 31 of the first pass ofthe tube nest. The portion 31 of the first ass of the tube nest may besaid to constltute the air cooler through which gaseous media maycirculate longitudinally owing to the staggered relation of theintermediate tube support sheet sections 28 and 29. Air and othernon-condensable gases are finally removed from the condenser through anoutlet conduit 32 which connects with the hood 30 at the entrant end ofthe first pass 15. In this way, the air is removed from the condenser atminimum temperature. In order that condensate may be removed from thecondenser at as high a temperature as possible, the condensate outlet 33is preferably located at the opposite end of the shell structure. thatis, at the end adjacent the discharge or warm end of the first pass 15.

In operation, steam is admitted to the inlet 11 and, first of all.enters the second pass 16 of the tube nest. However, as statedheretofore, the end 13 of the second pass 16 is relatively cold whilethe end 12 is relatively warm so that a region of high heat headprevails at the end 13 of the second pass and a region of low heat headat the end 12. Consequently, the steam in the spacious inlet 11 has anatural tendency to flow toward the end 13 so that more steam to becondensed is allotted to the cold end 13 and less to the warm end 14.This is a condition which is theoretically ideal and which has obtainedin mostcondensers of the prior art.

In passing through the second pass 16, some of the steam is condensedand falls downwardly to the bottom of the shell structure from which itis drained through the condensate outlet. 33. However, the remainingportion of the steam enters the distribution space. 17. As statedheretofore, the volume of the distribution space 17 is such that thesteam entering therein may redistribute itself longitudinally inaccordance with the reversed locations of the high and low heat heads inthe first pass. In other words. the distribution space allows some ofthe steam to flow in the direction of the tube sheet 12 and more steamis. therefore. distributed to the cold end of the first pass and less tothe warm end.

Referring. at this time. to the condensers of the prior art. applicantwishes to emphasize that. as thesecondmisers have heretofore beenconstructed, the distance inter- I the order of 18 inches.

from redistributing itself longitudinally.

In accordance with my invention, I prefer to make this distance of suchample proportions that the longitudinal velocity of vapor fiow throughthe passage 17 will be no higher than the velocity of the steam lea-ving the second pass of the tube nest or en tering the first pass. Inaccordance with my invention, the distance intervening between the firstand second passes may be of However, the latter figure may varyconsiderably as it is dependent upon the amount of tube surface of thecondenser. the lengthof the tube nest. the width of the tube nest. thevelocity of the steam through the condenser, etc, I

It will. therefore. be apparent that, by means of the distributionpassageway 17. more steam is directed to the cold end 12 of the firstpass and less steam to the warm end 13. Condensate created in the firstpass commingles with the condensate created in the second pass and isdrained through the outlet 33 while the non-condcnsable gaseous mediatravels longitudinally through the first pass in a somewhat tortuouspath. as defined by the tube sheet sections 28 and 29, and is finallyremoved through the outlet 32. As the outlet 32 is adjacent to thatportion of the condenser wherein the cooling water first enters, it isevident that the air and other non-condensable gaseous media are removedat minimum temperature.

Referring now to Fig. 3, I show an embodiment of my invention wherein aconsiderable portion of the first pass of the tube nest is set asideprimarily for cooling the air and other non-condensable gaseous Inthisembodnnent. I provide, in'

media. the longitudinal distribution space 17, a batfie 35 which extendstransversely across the full width of the tube nest and which.longitudinally, slopes downwardly in the distribution space 17 from theend tube sheet 12 toward that intermediate tube sheet 25 which isdisposed adjacent to the end 13 ot' the condenser. The first pass 15 ofthe tube nest is supported by sectional tube sheets 3(3. 37 andifilarranged to atlord longitudinal circulation of gaseous incdiathrough the first passot the tube nest to an air or non-comlensablev gasoutlet 39 located adjacent to the end I! of the condenser.

In operation, steam is admitted through the inlet 11 and is distributedto the second pass of the tube nest 14 in the same manner as theembodiment shown in Fig. 1. That portion of the steam which is notcondensed in the second pass of the tube nest enters the distributionspace 17 and is directed by the bafiie 85 to the end 13 of the firstpass, which end serves as an entrance chamber for the air cooler, thatis, that portion of the tube nest disposed below the baflie 35. Thebafile 35,'in this embodiment, isolates the cooler from the second passso that all uncondensed "and non-condensable media from the second passflow naturally to the end 13 of the first pass as this is the exposedzone of thenext highest heat head. Uncondensed gaseous media then flowslongitu'dinally through the portion of the first pass disposed below thebafile 35 to the outlet 39, thus traversing the coldest portion.

second pass into the entrant portion of the cooler embodied in the firstpass and represented by that portion of the tube nest which is disposedbelow the bafile 35. The arrangement shown in Fig. 3 provides for veryeffective cooling ofthi l air and noncondensable gaseous media priortotheir removal from the condenser. It will, therefore, be apparent that.by the aid of a distribution space such as 17, a very substantialportion of the first pass of the tube nest may be utilized primarily forcooling purposes.

Referring now to Figs. 4 to 7, inclusive, I show still anotherembodiment of my invention wherein the condenserl is of the radial flowtype. In this embodiment, the tube nest is divided into a lower firstpass 41 having a. width substantially less than that of the interior ofthe shell structure 10 and having its upper surface preferably formed inthe shape of a semi-circle. Surrounding the first pass 41 on three sidesthereof is'a crescent-shaped second pass tube nest section 42 which isso spaced from the f rst pass as to form an intervening, longitudinally-extending distribution space 43, which also is substantiallycrescent-shaped. The outer contour of the second pass 42 is so spacedfrom the interior of the shell structure as to form. with the latter, anintervening steam delivery space 44 surrounding the outer'periphery ofthe first pass tube nest section. As shown in Fig. 6, thewater hon 19 isprovided with a division wall 50 so shaped as to direct the coolingwater. from the inlet 19 into the first pass section of the tube ncstandto receive cooling water from the second pass section of the tube nestand to discharge it to the outlet 21.

, condensed while the temperature 0 For supporting the tube nestintermediate of the and tube sheets 12 and 13, suitable intermediatetube supporting sheets 45 are rovided which sheets, as shown particuarlyin iig. 7 are provided with suitable openings 46 located in thelongitudinal dis- I tribution space 43. The openings 46 are of suchsubstantial flow-area as not to interfere with the free longitudinalcirculation of gaseous media in the distribution space 43. The firstpass section 41 of the tube nest is so formed as to embody alongitudinally-extending cavity or core space 47 arrangii to permitaseous media which has not 11 condense in the tube nest to enter thecore space 47 and to flow toward an air at the cold or cooling waterentrant end 0 the first pass of the tube nest, is a cupshgped baflle 51for directin the gaseous m is from the core space racIially outward intosurrounding portions of the tube nest before the same enters the entrantportion 52 of the air ofi'talre 48. That portion of the tube nest whichsurrounds the cup-shaped baflie 51 and the entrant portion 52 of theoiftake 48 may be said to constitute an air cooling section and in orderthat condensate may be prevented from raining down into this portion ofthe tube nest, an arcuate bafile 53 is disposed above the cold orcooling water entrant end of the first pass of the tube nest.

In operation, steam enters the shell structure through the inlet 11 andsurrounds the second pass 42 of the tube nest in the steam deliveryspace 44. The steam then travels in substantially radial directionsthrough the section 42- of the tube nest and enters the intermediatedistribution space 43. As in the previous embodiments, the distributionspace 43 has such ample, transverse flow-area as will permit the steamto redistribute itself longitudinall before entering the first passsection 41 of the tube nest.

he steam entering the first pass 41 of the tube nest travels inwardlytoward the core space 47 and the uncondensed gases finally enter thecore space 47 and flow longitudinally toward the ofi'take 48. However,before enterin the entrant portion 52 of the ofi'take 48, these gasesare deflected into the tube nest by the bafile 51 so that, when theyeventually reach the air offtake 48, their condensable component hasbeen com letely their non-condensable components has been reduced to aminimum. Condensate formed in all ortions of the tube nest drainsdownwar ly to the bottom of the shell structure and is dischargedthrough the outlet 33.

From the fore oing description, it will be apparent that I ave evolved anovel form of multi-pass condenser wherein suitable distribution spacesare provided in order that as the steam approac es successive passes ofthe tube nest, it may redistribute itself to suit the changed locationsof the heat heads. As a result, condensers so constructed make moreeffective use of the entire coolin surface of the tube nest. While Ihave s own my invention as being applicable to condensers of thetwo-pass type, nevertheless it is to be understood that my invention isequally applicable to condensers wherein the tube nest embodies morethan two passes.

While I have shown my invention in three forms, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various other changes and modifications, without departing from thespirit thereof, and I desire, therefore, that only such limitationsshall be placed thereupon as are imposed by the nor art or as arespecifically set forth in the appended claims.

What I claim is:

1. In a condenser, the combination of a shell structure, a tube nestextending longitudinally through the shell structure and embodying firstand second passes, water boxes associated with the ends of the tube nestand providing for the circulation of cooling water through the firstpass of the tube nest and thence through the second pass of the tubenest, an inlet rovided in the shell structure for distri uting gaseousmedia to be condensed to one of the passes of the tube nest,longitudinally-extending pgssageway means of substantial flow area tweenthe passes for distributing gaseous media to the other pass of the tubenest, and means communicating with the interior of the shell structurenear the entrant end of that ass in which the cooling water is firstcircu ated for removing non-condensable gaseous media from the shellstructure.

2. A condenser as claimed in claim 1 and including condensate outletmeans connecting with the shell structure at the end thereof adjacentthe discharge end of that pass in which the cooling water is firstcirculated.

3. In a condenser, the combination of a shell structure having an inletfor aseous media to be condensed and an out et for condensate, a tubenest extending longitudinally throu h the shell structure, water boxesassociate with the ends of the tube nest and providing for circulatingcooling water through the tube nest in a plurality of passes, apassageway means extending longitudinally through the shell structureand separating adjacent passes of the tube nest for affordingunrestricted longitudinal distribution of gaseous media between theasses, and means communicating with the interior of the shell structurenear the en- ,trant end of that pass of the tube nest in which thecooling water is first circulated for removing non-condensable gaseousmedia from the shell structure.

4. A condenser as claimed inclaim 3 wherein the adjacent passes of thetube nest are separated at least 10 inches apart.

5. In a condenser, the combination of a shell structure having an inletfor gaseous media to be condensed, a tube nest extending lon itudinallythrough the shell struc-* ture and divided, transversely, into first andsecond passes, one of said passes being disposed relatively near theinlet and the other of said asses being disposed relatively removed romthe inlet, water boxes associated with the ends of the tube nestandproviding for circulating coolin water through the first pass and the.secon pass in series, passageway means separating the asses of the tubenest for aflording longitu inal distribution of steam to the passremoved from the inlet, and means for withdrawing noncondensable gaseousmedia from near the cooling water entrant'end of'the pass removed fromthe inlet.

6. In a condenser, the combination of 'a shell structure having an inletfor gaseous media to be condensed, a tube nest extending lon itudinallythrough the shell structure an divided, transversely, into first andsecond passes, a water box associated-with one end of the tube nest andarranged to supply cooling water to the first pass of the tube nest andto receive cooling water from the second pass of the tube nest, a waterbox associated'with'the other end of the tube nest for receiving thewater from the first pass and for directing it to the second pass,passageway means intervening between the passes of the tube nest andproviding for unrestricted circulation of gaseous media in a directionfrom the cooling water entrant end of the second pass toward the coolingwater entrant end of the first pass, and means communicating with theinterior of the shell structure for removing air from the entrant end ofthe first ass. p 7. In a condenser, the combination of a shellstructure, a tube nest extending longitudinally through the shellstructure and embodying first and second passes, tube sheets located ateach end and intermediate of the ends of the tube nest for supportingthe latter, water boxes associated with the end tube sheets andproviding for the circulation of'cooling water through the first pass ofthe tube nest and thence through the second pass of the tube nest, aninlet provided in the shell'structure for distributing gaseous media tobe condensed to one of the passes of the tube nest,longitudinally-extending passageway means separating the passes of thetube nest, said passage sway means including openings ofsubstantialflow-area provided in the intermediate tube supporting sheets, and meanscommunicating with the interior of the shell structure near the entrantend of the pass in which the cooling water is first circulated forremoving non-condensablegaseous media from the shell structure.

8. In a condenser, the combination ofa shell structure having an inletfor gaseous media to be condensed, a tube nest extending lon itudinallythrough the shell structure and divided, transversely, into "first andsecond passes said first pass being disposed adjacent to the side of the.shell structure remote from the inlet and said second pass extendingabout the exposed periphery of the first ass and defining, with theinterior of the s .ell structure, a longitudinally-extending steamdelive space surrounding a substantial portion 0 the second pass,longitudinally-extending passageway means separating the first andsecond passes and providing a second longitudinally-extending steamdelivery space, means forcirculating cooling water through the passes ofthe tube nest in series, and means communicating with the interior ofthe shell structure for withdrawing air from an interior portion ofthe'first pass and from the cooling water entrant end thereof.

9. In a condenser, the combination of a shell structure havin an inletfor gaseous media to be condense a first pass group of coolin tubesextending longitudinally throng the shell structure and disposedadjacent to the side of the shell structure remote from the inlet, saidfirst pass group being formed with a substantially semi-circularperiphery on the entrant side thereof, asubstantially crescent-shapedsecond pass roup of cooling tubes extending longitudinally through theshell structure between the inlet and the first pass group and so spacedfrom the latter as to form a substantially crescentshaped,longitudinally-extending passageway for the longitudinal distribution ofgaseous media to the second pass group, means for conveying coolingwater through the first passgrou and the second pass group in series, anmeans communicating with the interior of the shell structure forremoving non-condensable gaseous media from the cooling water entrantend of the first pass group.

10. In a condenser, the combination of a shell structure having an inletfor gaseous media to be condensed, a substantiall circular tube nestextending longitudlnally through the shell structure, an'inner group oftubes and an outer group of tubes ema m o wbodied in the tube nest andspaced from each other so as to form an intervenin distribuztion spacesurrounding a substantial ortion and providin for the circulation ofcooling water throng the two groups of tubes in series, and meanscommunicating with the interior of the shell structure for withdrawingnon-condensable gaseous media from the inner group of tubes and from thecooling water entrant end thereof.

11. In a condenser, the combination of a shell structure havin an inletfor aseous media to be condense and an outlet or condensate, a tube nestextending longitudinally throu h the shell structure, water boxesassociate with the ends of the tube nest and providing for circulatingcooling water through the tube nest in a plurality of passes, passagewaymeans extending longitudinally through the shellstructure and separatinadjacent passes of the tube nest for afi'or in unrestricted longitudinaldistribution o gaseous media between the asses, passageway meansembodied in the rst of the asses of the tube nest for afiording longituinal circulation of gaseous media in a direction from the coolin waterdischarge end of said pass towar the cooling water entrant end thereof,and air outlet means connecting with the interior of the shell structurenear the entrant end of the first pass of the tube nest.

12. A condenser as claimed in claim 11 and embodyin means for directinggaseous media circulating through the passageway means in the first passover portions of the coolin tubes in the first pass.

13. n a condenser, the combination of a shell structure, a tube nestextending longitudinally through the shell structure and embodying firstand second asses, tube sheets located at each end and intermediate ofthe ends of the tube nest for supporting the latter, water boxesassociated with the end-tube sheets and providing for the circulation ofcooling water through the first pass of the tube nest and thence throughthe second pass of the tube nest, an inlet provided in the shellstructure for distributin gaseous media to be condensed to the second paof the tube nest, longitudinally-extending passageway means separatingthe passes of the tube nest for distributing gaseous media to the firstpass of the tube nest, said passageway means including openings ofsubstantial flow-area provided in the intermediate tube supportingsheets, passagepassageway means including openings provided in theintermediate tube supporting 1 sheets, and air outlet means connectingwit the interior of the shell structure near the entrant end of thefirst pass of the tube nest. nest.

14. A condenser as claimed in claim 13 and embodying bafile means disosed within the first pass of the'tube nest or directing gaseous mediacirculating through the passageway means in the first pass over portionsof the cooling tubes in the first pass.

15. In a condenser, the combination of a shell structure havin an inletfor aseous media to be condense and an outlet or condensate, a tube nestextending longitudinally through the shell structure, water boxesassociated with the ends of the tube nest and providing for circulatingcooling water through the tube nestin a plurality of passes, passagewaymeans extending longitudinally through the shell structure and separatinadjacent passes of the tube nest for atlordin unrestricted longitudinaldistribution 0% passes, a longitudinally-extending cavity gaseous mediabetween the embodied in the first pass of the tube nest,

and air withdrawal means connecting with the cavity near the end thereofadjacent to the cooling water entrant end of the first pass of the tubenest.

16. In a condenser, the combination of 'a shell structure havin an inletfor aseous media to be condense and an outlet or condensate, a tube nestextending longitudinally through the shell structure, water boxesassociated with the ends of the tube nest and I providing forcirculating cooling water through the tube nest in a plurality ofpasses, passageway means extending longitudinally through the shellstructure and separatin adjacent passes of the tube nest for afior inunrestricted longitudinal distribution o gaseous media between thepasses, a core space extending longitudinally through the first pass ofthe tube nest for affording longitudlnal circulation of gaseous media inadirection from the cooling water discharge end of said pass toward thecooling water entrant end thereof, bafile means disposed in the corespace for deflectin gaseous media from the core space towar surroundingportions of the first pass of the tube nest, and air withdrawal meansconnecting with the core space near the end thereof adjacent the coolingwater entrant end of the first pass of the tube nest.

17. In a condenser, the combination of a shell structure, a tube nestext-ending longi tudinally through the shell structure andembodyingfirst and second passes, tube sheets located'at each endandintermediate of the ends of the tube nest for supporting p thelatter, water boxes associated with the end tube sheets and providingfor the circulation of cooling water through the first pass of the tubenest and thence through the second pass of the tube nest, an inletprovided in the shell structure for distributing gaseous media to becondensed to the second pass of the tube nest, longitudinall -extendingpassageway means separating t 1e passes I of the tube nest fordistributing gaseous media to the first pass of the tube nest, saidpassageway meansincluding openings of substantial flow-area provided inthe intermediate tube supporting sheets, a cavity extendinglongitudinally through the first pass of the tube nest for affordinglongitudinal circulation of gaseous media in a direction from thecooling water discharge end of said pass toward thercooling waterentrant end thereof, said cavity including openings provided in theintermediate tube supporting sheets, bafiie means disposed in the cavityfor deflecting gaseous media from the cavity over surrounding portionsof the first pass of the tube, nest, and air outlet means connectingwith the interior of the shell structure near the cooling water entrantend of the first pass of the tube nest.

In testimony whereof, I have hereunto subscribed my name this 23rd dayof May,

J OHN H. SMITH.

